create_NSSH: "Conferences of the NCSS, Subpart A" missing from README

[brownag]

The subpart 602A links and sections are missing from the table in README.md, but the content is here: https://github.com/ncss-tech/SoilKnowledgeBase/blob/main/inst/extdata/NSSH/602/602A.txt

The one section (602.00 Definition) appears to show up correctly in the table of contents